I had access to a bunch of leaked Amazon FBA courses and they were very basic
Let's say they advertise their course is 10 hours long but what they put is basic bulls**t like how amazon works etc. They spend very little time on most important things like how to set up the PPC campaign. One of the courses costed 5K USD if I paid for it that much I would be just mad...
My advise is first test the waters and start small, try to gain experience, don't go all in with your capital
And as someone mentioned it's harder now but still profits to be made for sure, you need to find something very niche and a good branding is important too. Make professional photos of the products! It's crucial for ecommerce